Protective device



May 15, 1934. D, l. BOHN 1,959,017

PROTECTIVE DEVICE Filed May 3l, 1932 G O O Vfl/mm mm lll/111101101111@ INVENTOR.

o/V47 f. Doo/wv A TT ORNE Y.

Patented May l5, 1934 PROTECTIVE DEVICE Donald I. Bohn, Pittsburgh, lfa., assignor to Aluminum Company of America, Pittsburgh,

Pa., a corporation of Pennsylvania Applicaummy a1, 1932, serial No. 614,599

9 Claims.

This "invention relates to electrical devices adapted to detect and correct mis-alignment between the fixed and rotating parts of a machine. It nds particular application to the detection of mis-alignment of the rotating elements of heavy machinery such as the shafts of turbines and the like.

An object of the invention is to provide a del vice capable of detecting mis-alignment of shafts or other rotating elements so that damage to such elements and to adjacent machinery may be avoided or greatly minimized either by correctlng the mis-alignment or by shutting down the machinery before serious damage has been eil'ected.

In the drawing, Fig'. 1 illustrates a safety device embodying my invention as applied to the shaft of a vertical hydraulic tuibine for which use it is particularly well adapted.

Fig. 2 is a schematic drawing of another modiflcation of my invention, also shown in conjunction Vwith .a hydraulic turbine.

Referring to Fig. 1, 1 is an electrical generator of conventional type and 2 is a thrust bearing which carries the load on the rotatable shaft 3. The load is transmitted to the thrust bearing 2 by the collar 4 rigidly attached to the shaft 3 which is rotatable in the bearings 5 and 6. Through the scroll case 7 is admitted the fluid which drives the turbine wheel 8. Mounted in the scroll case are deflector vanes 10 which direct the fluid into the movable vanes 11 mounted in the speed-ring assembly which is designated in its entirety by 12. These movable vanes, which regulate the speed of the turbine, l,are actuated by hydraulic cylinders 13 which rotate the actuating ring 14 to which are attached the movable vaneoperating arms 15. The turbine wheel 8 is rigidly attached to the shaft 3 so that the rotation of the wheel under the action of the fluid from the scroll case serves to rotate the shaft and the generator rotor 16. 4The various parts making up the speed ring assembly 12 and the wheel 8 are so constructed as to form more or less effective seals against the leakage of fluid.

' To secure a high efficiency from the turbine by minimizing leakage, it is necessary that the clearances between the wheel 8 and the speed ring assembly 12 be as small as possible. For example the clearances 17 between these parts may be as small as 0.010 inch. It is thus apparent that any appreciable vibration or mis-alignment of the shaft 3 will cause the wheel 8 to contact the speed ring assembly 12. As these parts of the turbine are usually invisible to the operators, such contact between the moving wheel and the stationary parts may not be noticed until considerable damage may havey taken place by reason of the abrasion between the contacting parts. Various expedients have been resorted to in the past to minimize such damage as by providing theparts with replaceable wearing surfaces. However', if the abrasion continues for some time, these wearing surfaces may be severely damaged necessitating the complete dismantling of the machine for e5 the renewal of the abraded parts.

'I'he device which embodies my invention comprises broadly electrical means responsive to contact between the fixed and rotating parts of any mechanism. While such means may take difierent forms, it preferably comprises, as in the embodiment herein shown, means for producing an electromagnetic field around the shaft 3, such as a toroidal Winding or coil 18 which preferably is wound about a core 19 of laminated transformer 75 iron or some other material having a greater permeability than air. The core is not essential to the operation of the invention, as a field of sufficient intensity may be obtained by increasing the number of ampere turns of the coil. The Winding or coil 18 is electrically connected to, and energized by, a source of alternating current through a suitable power measuring device such as a wattmeter 20, by means of which the electrical input to the coil may be measured. 'I'he g5 coil is placed about the shaft 3 and is so positioned with respect to the axis of the shaft as to form a normally open electric circuit through the shaft so that if the wheel 8 comes in contact with the speed ring assembly 12 the circuit will be 90 closed and an electric current induced by winding 18 will be caused to iiow through the circuit comprising the shaft 3, the wheel 8 and one of v the bearings on the shaft. If the bearings 5 and 6 are made of some non-conducting material such 95 as lignum vit a special electric contact with the shaft may be provided, the only essential requirement for this Contact being that it be placed on the opposite side of the coil 18 with respect to the wheel 8. 1

It will be seen that this circuit, which will be closed by the contact ofthe wheel 8 with the speed ring assembly 12, is the equivalent of a. single turn secondary winding superimposed on the primary winding of a transformer. Thus, when this secondary circuit is open a certain power input, substantially equal to the conductor and core losses of the coil, is measured by the wattmeter 20, but when the secondary circuit is closed by the Wheel 8 coming in contact with 110 l nism, such as a systemof relays, to actuate a valveor thelike to stop the iiow of iiuidk to the turbine. Such adevice isillustrated sche'l matically in Fig. 2. A toroidal coil 18 surrounds the turbine shaft 3 rotatably lmounted in the bearing 6 and to-which is fixed the turbine wheel 8'.. The electrical path between the speed ring 12 and the shaft 3' is shown by the dotted line 21 terminating in the shaft bearing 6'; This path can be a separate conductor as shown, orthe various parts o the turbine assembly can be used to conduct the current which would :dow should the wheel 8 move through the clearance space 17' and touch the speed ring. When such a circuit is formed the changed value of current in the conductors 22 feeding the coil 18' energizes a system oi relays 23 serving to operate a control system 24, such as is well known in the art to close the valve 25 in the penstock 26 and shut off the ow of water to the turbine wheel.

In the foregoing description and explanation of my invention the particular forms of apparatus described have been selected for purposes of illustration as preierredembodiments of my in "vention, butvariations therein maybe made without departin'g'rom the nature and ,scope of my invention except as dened in the claims.

I claim: u Y

l. A device for' indicating contact between the fixed and rotating parts of a `turbine or the like comprising a winding energized by a source of alternating -current and an electric circuit superimposed on said winding in inductive relationship' therewith and adapted to be closed bythe contact of a rotating part with a fixed part, said rotating parts forming a part of said superimposed circuit.

2. A device for indicating contact between the iixed androtating parts of a turbine or the likecomprising a winding Aenergized by a source of alternating current, kmeans for indicating the magnitude of said current and an electric circuit superimposed on said winding in inductive relationship therewith and adapted to be closed by the contact of a rotating part with a xed part, said rotating parts forming a part of said super'- imposed circuit.

3. In aturbine or the like, liiired parts, rotatable parts adjacent said fixed parts, means for controlling the movement of the rotatable parts, electrical means responsive to contact between the" fixed and moving parts and comprising a winding energized by a source of alternating current andan electric circuit-superimposed on said 'comprising a primary circuit' surrounding said winding, m inductive relationship therewith, said rotatable parts forming a part of said superimposed circuit and said electrical means actuating v said controlling means.

4. In a turbine, a speed ring, a wheel and wheel shaft rotatably mounted therein, and means for indicating contact between said speed ring and the rotatable parts mounted therein, said-.means shaft and a secondary circuit in inductive .relationship with said primary circuit and adapted to be closed by contact between said speedA ring and said rotatable parts, said shaft forming apart of said secondary circuit.

' 5. In a turbine, a'speed ring, a wheel and wheel shaftl rotatablymounted therein, means for in dicating contact between'said speed ring and the rotatable parts comprising a primary circuit in the form of a toroidal winding'ene i .w a source of alternating current and surrounding said shaft, and a secondarycircuit in inductive relationship with said primary circuit and adapted to beA closed by contact between said s lring and said rotatable parts, said shaft forming.

' relationship with vsaid primary circuit, said sec= ondary circuit comprising the contacting parts. im

7. In a turbine, xed parte and moving parts and'means for detecting abrasive contact between said xed and movingV parts, said means comprising a primary circuit surrounding one or said moving parts and a secondary circuit in inductive Hg relationship with said primary circuit and adapted to be closed by contact between said xed and said moving parts, said surroundedv moving part forming a part of said secondary circuit.

8. A device for indicating contact between the i2( xed and rotating parts of a turbine comprising a constantly energized primary circuit and a normally open secondary circuit in inductive rela tionship with said primary circuit and adapted to be closed by contact between said xed and rotating parts, said rotating parts forming a part ,f of said secondary circuit.'

`ci said fixed and rotating parts, said secondary circuit being adapted to be closed by contact between said xed and rotating parts.

- DONALD I. BOM. 

